1. Field of the Invention
The present invention relates to a liquid transporting apparatus which transports a liquid.
2. Description of the Related Art
As a liquid transporting apparatus, an ink-discharge head which discharges an ink on to a printing medium such as a recording paper has hitherto been known. Such ink-discharge head includes a channel unit which has a plurality of individual ink channels including pressure chambers which communicate with nozzles, and an actuator which applies a pressure to the ink in the pressure chambers (Refer to Japanese Patent Application Laid-open No. 2003-326712 for example). However, in such ink-discharge head, as it is necessary to form individual ink channels of a multiple number of complex shapes in the channel unit, a manufacturing cost tends to become high. Moreover, for discharging a fixed quantity (a predetermined quantity) of ink, it is necessary to make a volume of the pressure chamber to be more than a predetermined volume. It is difficult to arrange closely (high integration) such individual ink channels having the complex shape including the pressure chambers, and therefore it is difficult to make the ink-discharge head to be a small size.
In view of the abovementioned situation, the inventor of the present invention has proposed a liquid transporting apparatus which transports an ink by an electrowetting phenomenon, as an apparatus which is capable of transporting a liquid, having a structure simpler than a structure of the conventional ink-discharge head (Refer to Japanese Patent Application Laid-open No. 2006-35640 for example). This liquid transporting apparatus includes a substrate in which a plurality of liquid channels is formed, individual electrodes (first individual electrode and second individual electrode) which are arranged at the middle in each of the liquid channels, and an insulating layer which covers the individual electrodes. When a voltage (driving electric potential) is not applied to the individual electrodes, a wetting angle of a liquid with respect to a surface of the insulating layer covering the individual electrodes is high, and the liquid cannot move onto the surface of the insulating layer. When the driving electric potential is applied to the individual electrodes and an electric potential difference is developed between the individual electrodes under the insulating layer and the liquid on the insulating layer, the wetting angle of the liquid with respect to the surface of the insulating layer becomes small (electrowetting phenomenon), and the liquid can move onto the surface of the insulating layer covering the individual electrodes. According to this arrangement, it is possible to transport the liquid independently in each of the liquid channels, only by changing (switching) the application of the driving electric potential to the two types of electrodes (first individual electrode and second individual electrode), without complicating the structure of the liquid channel.